Fix unescaped name argument in cache macro.

[evetion]

Fixes https://github.com/SciML/OrdinaryDiffEq.jl/issues/2158

Checklist

• [x] Appropriate tests were added
• [x] Any code changes were done in a way that does not break public API
• [x] All documentation related to code changes were updated
• [x] The new code follows the contributor guidelines, in particular the SciML Style Guide and COLPRAC.
• [x] Any new documentation only uses public API

Additional context

As discussed in the linked issue, the @cache macro generated the line full_cache(var"#329#c"::OrdinaryDiffEq.RK_ALGCache) = begin, specifically namespacing RK_ALGCache (leading to ERROR: UndefVarError:RK_ALGCachenot defined), because RK_ALGCache was defined elsewhere (Main in this case). This is fixed by escaping the name of the struct.

I also removed a perfect duplicate cache macro (and added an import) in the lib/OrdinaryDiffEqExtrapolation code, possibly put there because the original macro didn't work?